Pressure-relation gage.



E. G. BAILEY.

PRESSURE RELATION GAGE.

APPLICATION FILED III/m2o. 1913.

l 9 l 5 A 1l. 4., Paented Sept. 11, 1915.

E. G. BAILEY.

PRESSURE RELATION GAGE.

APPLICATION FILED III/111.20. 1913.

1,158,414., Pmendsept. 14, 1915.

v h I 2 SHEETS-SHEET 2.

IIIII l INI" lll ERVIN G'. BAILEY, OF NEWTON HIGHLANDS, MASSACHUSETTS.

PRESSURE-RELATION GAGE.

or more pressures which operate on the in-' strument. The generalexpression of the resultant of this relation is (p1-pa NPL?) in which Rrepresents resultant, and p1, p2,

p3 and p4 represent the four different pressures, while the symbol frepresents function, indicatinga more complex relationl than merely thesimple ratio of two differences of pressures. In some cases thisfunction may be such as to leave the resultant equal tot-he simple ratiobetween the two differences; and, in some cases, pf* may be equal to p1,while, in other cases, p4 may be equal to p2, thus leaving only threepressures necessary to operate the instrument, and-*indicate thedesiredV relation.

lVhile it is necessary to modify, readjust or rearrange some of theworking parts of the instrument embodying this invention, in order toadapt it for use under different conditions, the principle of theoperation is the same in all cases and depends upon utilizing, as oneoperating element ofthe instrument, a movable part acted on by a forcewhich varies as some function of a difference between two of ythepressure factors; and utilizing as another part of the instrument amovable part acted on by a force which varies directly as a differencebetween two of the pressures; and mechanically arranging said elementsso that the respective forces acting on them are opposed to eachother.

Figure 1 is a vertical section, partly in elevation, of an instrumentembodying the invention; Fig. 2 is a plan view of the same, partly insection; Fig. 3 is a vertical section, partly in elevation, of aninstrument of Specification of Letters Patent. Patenugd @9pm 314i, 1915Application led March 20, 1913.

Serial No. 755,594.

modified construction; and Fig. 4 is a similar View of another modifiedform of instrument. A

The operation. of the instrument can be readily understood by describingit as arranged to be used for indicating the relation between the rateof flow 'of fuel oil to a boiler furnace, andthe amount of steamgenerated in the boiler, in which case there are four pressures whichconstitute the factors entering into the equation, the instrument shownin Fig. l being adapted, for this purpose; or, by describing it be usedfor indicating the resistance of the fuel bed in a furnace, as comparedwith some substantially constant resistance through which the lfurnacegases are flowing. In the latter case,only three pressures are involvedas factors, and the instruments shown in Figs. 3 and 4 are arranged andadapted for this use. It isto be understood, however, that by slightmodifications and adjustments of the working parts the instrument can be'applied to a variety of useful purposes.

Referring to Fig. l, the instrument therein shown consists of a closedcase 1 having a partition 2 which divides it-into two chambers, the saidpartition having an off-set 3 through which extends a shaft 4, so thatlevers 7 and 8 can be fastened to said shaft and at the same time can belocated, respectively, inthe different chambers. 'To prevent leakage,the shaft bearings are suitably packed where the shaft passes throughthe walls of the chamber. The said shaft 4 is free to oscillate in itsbearings 5, and all the parts are balanced by means of an adjustableweight 6 mounted on one of the levers and capable of being moved alongthe same and fastened when equilibrium of moments is attained. Theinstrument is also provided with bells 9 and 10, which are suspended bylinks l2 and 13 from pivots 14 and 15 on the levers 7 and 8,respectively. Each of the chambers is partially filled with some liquidwhich seals the bottom of the bell which is suspended in it, and pipes16 and 17, which project upwardly through the liquid into the spacewithin the bells, are utilized to .-fconvey pressures which produceforces tending to cause upward movements of the bells, respectively. Thepressures which constitute the other factors of the equation areconveyed, respectively, into the chambers which contain the bells 9 and10, entering the chamber above the surface of. the liquid, so that thepressures conveyed through pipes 18 and 19, provided for the purpose,will act upon the respective bells in iopposition to the forces whichtend to cause'the upward movement-s thereof; also acting on the liquidsurrounding the bells, in opposition to the forces acting on the liquidinclosed inthe bells, lf, for example, the pipes 19 and 17 are connected`to the dynamic and static parts of a Pitot tube, or similar device indevice, so that the difference between the pressures in the pipes variesas some known function of the rate of flow of steam from a boiler, adefinite resultant force due to the difference between these pressureswill exist for any given rate of flow of steam and will f act on thebell 10. Similarly,'by connecting the pipes 18 ,and 16 to the dynamicand static parts of a Pitot tubefor similar` device 1n the pipesupplying oil to the boiler furnace,

- a definite force, due to the pressure differ* ence which exists forany given rate of flow of oil, will act on the bell 9.

For any glven rate of flow of oil burned with proper efficiency, adefinite amount` of steam should be generated, but the ratio ot4 therate .of flow of oil to the rate of flow of steam will vary with thelatter, being. a minimum when the boiler is working at its mostefficient rate, and increasing, either vdirectly or inversely as thecharacteristic elhciency curve of the boiler. Theinstrument is providedwith a scale 20 and an indicator 21 connected with the shaft 4, and thevarious parts are so arranged and adjustedthat all the mechanicalelements will be in equilibrium when the indicating member stands at a'certain mark on the scale,'which shows thatthe desired relation existsbetween the rates of flow of oil and steam throughqut 4their workingrange of variation. Further- `more, the arrangement is such' that theindicating member will move in one direction in case there is an excesssupply of oil, and 1n the opposite direction if there is a deficiency,

the movement being due to the forces acting on the bells. When the ratioof the pressure differences varies with the rates of iow, it isnecessary, inorder to maintain the indicating member in the stated,position when' the correct relation exists, to vary the intensity offorce per unit pressure difference acting upon one ,or the other of thebells. This variation is brought about, .in accordance with theinvention, by varying the horizon tal sectional area vof either or bothbells. In the construction shown, the horizontal sectional area of thebell 9 varies in a..suit able manner, while thehorizontal sectional areaof the bell 10 is uniform. The surface of the liquid inthe bell 9will'stand at a height above -thefsurface of the hqmd outside the bell,which height `is directly, proj` exerted upon the bell isequivalent tothe weight of that volume of the liquid which is above the'surface ofthe liquid outside (the volume displaced by the pipe 16 not beingexcluded). By suitably varying the area of the bell 9 and 'the height ofthe surface of the liquid in the chamber containing said bell, thevolume of liquid within the bell, above the level of the liquidsurrounding said bell, is caused to vary in any desired relation .to itsheight, and thereby any desired force per unit difference of pressuremay be obtained.

The shape of the bell cannot be varied after the instrument isconstructed, but the height of the surface of the liquid in the chambermay be varied in accordance with any desired function of the differencein pressures conveyed through the pipes 1S and 16. As shown in Figs. 1and 2, this may be accomplished by varying, from top to bot- Atom, theconfining limit of the liquid in the chamber, as by providing thechamber with a suitably shaped displacing member, the shape of which issuch as to vary the area of the liquid exposed at the surface as thelevel of said surfacevchanges. lVhen a separate displacing member isused, it may be made capable of vertical adjustment. Furthermore, thesaid displacing member may be in the form of a chamber, closed, exceptat the bottom, and sealed in the liquid; in which case the interior ofthe displacing member may be subjected to the same pressure as thatwithin the bell 9, whereby the displacingmember is also utilized as asup plement to said bell in the change of area of the liquid which isconfined in the bell and displacing member, compared to the area of theliquid outside. As shown in Figs. 1 and 2, the said displacing memberconsists of a vertically adjustable chamber 22, which is closed on allsides and at the top, but open at the bottom and sealed by the liquid.The said displacing member receives, through a branch pipe 23, the samepressure as that conveyed to the interior of the bell 9, so that theliquid rises inthe displacing member 22 to thesame height as it does inbell 9. The volume of liquid, which is held up in the' bell 9 anddisplacing mein ber 22, causes a lowering of the level of the liquid' inthe compartment outside of the said bell andmember, which change oflevel varies inversely as the remaining area of the free surface of theliquid outside, So that, by properly shaping the area of the member 22with respect to its own height, and with respect to the shape of thebell 9, the density of the liquid, and the surface area of the liquid,the level of the surface outside of the bell and displacing member isvaried as a definite function of the difference between ricami al theoutside and the inside pressures, thereby causing the force'per unit ofpressure difference to 'balance the force due to the dif,- ferencebetween the pressures acting on the bell 10, when the desired relationexists between the rate offlow of steam and the rate of flow of oil forany desired rate of flow of steam.

Taking the arrangement of the parts as shown in Fig. l, the operation ofthe instrument may be described as follows: Startlng with zerodifferences of pressures in the tw o compartments and the-mechanism inequilibrium, the pointer 21 is so positioned with relation to themechanism and to the scale 20 as to indicate the correct relationbetween the rates of flow (which is true whenboth are zero). With thefirst increments of pressure differences, the ratio of the resultingforce acting on the bell 9 to the force acting on the bell l0 will beinversely proportional to the areas of the two. A further increase inthe pressure difference acting on the bell 9 and 'displacing member 22will cause the liquid to `rise in the said bell and member above thenormal level of the liquid in the compartment, and the level of theliquid outside of the said bell and member will be lowered at a ratewhich is inversely propor tionalto the ratio of the combined area of thesurface inside of the bell and member to the area of the surface outsideof the bell and member, as is shown in Fig. l. f `With the relativeareas as shown, the level of the liquid outside of the bell and memberwill be lowered much faster than the level of the liquid inside thereofwill be raised, and the mean area of the surface of the liquid sustainedin the bell 9 bythe pressure difference will be increased, thusrequiring a, relatively less increase in the pressure difference actingon the bell 9 with relation to the increase in pressure differenceacting on the bell l0, to equalize the respective forces and cause theindicating member to remain stationary. This condition will continueuntil the rate of flow of steam and the rate of flow of oil `whichcorrespond to maximum efiiciency has been reached. Beyond that point,the pressure difference acting on the bell 9 will become such that therise of the surface of the liquid in the bell 9 and displacing member 22will be greater than the fall of the surface of the'liquid outsidethereof; and the mean area of the volume of liquid sustained in the bell9 will diminish, thus requiring an increase in the ratio of the pressuredifference acting on said bell 9 to that acting on the bell 10. It isevident, therefore, that the equation i has been satisfied when thefunction represented by f is dependent upon the boiler etliciency curveas affected by the rate of driving. lin case the force due to thepressure difference acting on the bell 9 is greater than is necessary tobalance the force due to the pressure difference acting on the bell 10,and thereby to maintain the necessary equilibrium of forces to keep theindicating member 2l in the desired position, the bell `9 will movedownward and the mean area of the surface of the liquid sustained insaid bell will be decreased to correspond, thereby reducing the forcecaused by the pressure difference until it again equals the balancingforce acting on'the other bell, so that equilibrium is restored.Therefore, no further movement will take place, and the position of theindicating member will show that the rate of flow'of oil is greater thanit should be with relation to the rate of flow of steam, andapproximately to what extent. This indicates that the desired efliciencyis not being maintained because of `faulty conditions which should becorrected.

The general shape of the bell 9, as well as that of the displacingmember 22, is determined from empirical data relative to boilerefliciency at different rates. shapes have been determined and theinstrument constructed accordingly, it is only necessary to adjust thelevel of the liquid and the vertical position of the displacing member22, as by a nut 25, in order to take care of the minor differencesbetween individual boilers and furnaces. The normal equilibrium of themechanical parts of the device may be further modified by properlyadjust`4 ing the counterweight Tn F ig. 3, T have shown a modified formof instrument in which -there are only three pressure factors involved,and the resultant desired is expressed by the equation f (logra) and inthe actual form of instrument shown, the f function is unity and therelation between the pressure differences is proportional to the simpleratio of ferences. Tn this instrument, the arrangement of the bells andthe case is substan tially the same as previously described, ex,- ceptthat the closed case is 'not divided above the bells, although theliquid which seals the bells is in different compartments.

The pressure p1 is admitted to the lcasing through the pipe 26, and actson the outside of bothv bells, as well as on the surface of the liquidsurrounding them. Pressures p2 and p3 are conveyed through pipes 27 and28,-to the interiors of the bells 10 and 9, respectively; and whenequilibrium of the parts is upset by a departure from the desired ratio,it is restored after a certain movement of the parts has taken place, by

After these the pressure difthe effect caused through change of areasdue to the shape of the bell 9. The pressure p3 is also conveyed to-thedisplacing member 22 through the branch pipe 29. In this instrument, thearea of the bell 9 varies directly as its height, and the inside andoutside areas of thedisplacing member 22 also vary directlyas itsheight,increasing as the area of the bell 9 decreases. The bell and displacingmember are also of such size relative to the size of the chamber thatthe area of the liquid surrounding the bell 9 and displacing member 22equa-ls the combined areas of the liquid within said bell anddiswplacingmember when the bell 9 is in its -normal position.

The ratio between the two pressure differences 121-792 and v1-p3, whenthe indicating member 2l is in its normal position is `determined by theratio of the surface area -of the liquid within bell 9 when in itsnormal position, to the surface area of the liquid within bell l0, whichin turn is dependent upon the depth of liquid in the compartmentcontaining the bell 9, and is adjustable by adding or taking out liquiduntil the instrument is set for the desired ratio between the pressuredifferences. Any increase in pressure difference 291-273 will cause thesurface of the liquid to rise in the bell 9 and the displacing member22, and also to fall a like'amount in the space outside, on account ofthe ratio of areasas previously stated, so that the mean height of theliquid in bell 9 above the surface of the surrounding liquid remainsunchanged, and the total volume of liquid supported in the bell 9 variesdirectly with the pressure difference 791-7?, and equilibrium of forcesdue to pressure differences is maintained so long as pressure differencegi-p2 bears a constant ratio to pressure difference p1-p3, throughoutthe entire working range of pressure differences. Any deviation fromthis ratio will produce motion of the oscillating parts and byincreasing or decreasing the efective area of bell 9, equilibrium ofmoments will be automatically restored and the position of the 4 5oindicating member 21 with respect to the scale 20 willshowjthe amount ofdeviation from the normal ratio between the pressure differences.

In order that the change in position of the 'indicating member mayrepresent the change )in ratio, it is necessary to counteract the changein buoyant action upon the bells as.

one -sinks more deeply into the liquid and the other ,is raised from theliquid. This is accomplishedby means of a counterweight I30 supportedupon the rod 3l', as shown,

which is equivalent to having the center of gravity of the beam 32 andits rigid attachments, above the pivot 33, so that a moment isvintroduced by .its oscillation through a limited angle that issuhcientto counteract the moment due to the change in buoyancy hoods 3lfor the bells, the said hoods being closed at the top, but havinglateral openings 35 below the surface of the liquid for the lower endsof yokes 36 by which the bells are supported, the yokes being hung fromthe beam which corresponds to the levers 7 and 8 of Fig. l. Thedisplacing member is also dispensed with, and the change in effectivearea of the bell 9 is introduced into the relation, other than a simpleratio, which is desired, and represents the f function in the equation.In this instrument the pressure p2 is conveyed through pipe 37 to theinclosed space outside of the lbell lO'and to the inclosed space insideof the bell-9, while the pressure 721 is conveyed through the pipe 38 tothe inside of the bell l0, and the pressure p3 through the pipe 39 tothe outside of thebell 9, the tendency of both bells being to moveupward. As in other forms of instrument shown, any vaiiation from therelation desired will cause movement until equilibrium is restored bychange of area.

In order to vary the f function beyond the variation produced by thevariable area of the bell 9, the counterweight -lO may be so adjustedthat the indicator will stand in i some other than normal position forzero pressure'di'erences, and the force due to such counterweight willthen have a varying edect upon the position of the indicator, decreasingwith increase of the pressure difference 222-193 and causing thechanging relation of pressure differences necessary to satisfy theconditions with different intensities of pressure difference.

It is perfectly obvious that four different pressures may be applied tothe instruments shown in Figs. 3 and 4, or three pressures to theinstrument shown in Fig. 1.-

The underlying principle is the same throughout, and the minor featuresof difference shown in the several forms of instruments are capable ofapplication to any of them, and it is obvious that still furthermodification can be made without departing from the invention. What Iclaim is:

1. In a pressure relation gage, the combination with an oscillatablemember; of an indicating member adapted to be moved by said oscillatablemember; of two movable liquid sealed bells connected to saidoscillatable member," and each adapted to receive fluid pressure onopposite sides and producing opposing moments of force about the axis ofsaid oscillatable member, one of said bells having a varying horizontalsectional area; and means whereby the height l of the level of theliquid which seals the variable area bell is automatically varied inresponse to the pressures acting on said variable area bell.

2. In a pressure relation gage, the comi bination with an oscillatableindicating member; of two movable liquidfsealed bells con-nected toVsaid indicating member; means for subjecting each bell to fluidpressures outside and inside, one of said bells having a variablehorizontal sectional area; a chamber containing the liquid in which saidvariable area bell is sealed; and a displacing member of variablehorizontal cross-sec* tional area," located in said chamberl therebycausing the area of the free surface of the liquid in said chamber to bevaried with changes in the level of said liquid.

3. In a pressure relation gage, the combination with -an oscillatableindicating member; o-f two movable liquid sealed bells connectedto saidindicating member; means for subjecting each bell to fluid pressuresoutside and inside, one of said bells having a variable horizontalsectional area; a cham# ber containing the liquid in which saidvariablearea bell is sealed; a displacing member located in saidchamber, said displacing member comprising a chamber closed at the topand open at the bottom, and sealed in the same liquid as that whichseals the'variable area bell, said member'having a variable horizontalsectional area within and without; and means for subjecting the interiorof said displacing member to the action of the same pressure which actson the j interior of the variable area bell.

4. In a pressure relation gage, the combination with an oscillatableindicating member; of two movable liquid sealed bells connected to saidindicating member; means for subjecting each bell to fluid pressuresoutside and inside, one of said bells having a variable horizontalsectional area; a chamber containing the liquid in which said variablearea bell is sealed; a displacing member located in said i chamber; andmeans for vertically adjusting said displacing member.

5. In a pressure relation gage, the combination with an oscillatablemember; of an indicating member adapted to be moved thereby; two"movable liquid sealed. bells adapted to receive fluid pressure outsideand inside, said bells being connected to said oscillatable member andproducing opposing forces due to the pressure differences acting on saidbells; and meansv whereby equilibrium of all said forces, includingthose produced by the various parts ofthe mechanism itself, is obtained,and said indicating member caused to remain in a definite position solong as a definite relation exists between said nressure differences.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

ERVIN G. BAILEY.

Witnesses:

JAS. J. MALONEY, M. E. CovENEY.

